Portable appliance testing (PAT) describes the examination of electrical appliances and equipment to ensure they are safe to use. Electrical equipment can get damaged, develop faults, or the parts may deteriorate. This can happen for a number of reasons and, if not identified, can have serious consequences. Using electrical appliances or equipment that are not completely safe can result in serious injuries or even death.

A full PAT test includes both a visual inspection and a more in-depth check using special PAT testing equipment.  It forms part of Electrical Safety Inspection.

At the end of a PAT test, every appliance should be marked ‘Passed’ or ‘failed with the test results recorded.

PAT (Portable Appliance Testing)

Need for Portable Appliance Testing

PAT testing ensures that electrical appliances and equipment are safe to use. It guarantees that there’s little chance of accidental injury due to faulty electronics therefore reducing the risk to the user. The international standards that guide our inspection include BS 7671- 17th Edition wiring regulations and The Electricity at Work Regulations 1989. Apart from that, we also meet local standards such as Occupational Health and Safety Act, 2007.


In depth PAT testing focusses on three aspects

  1. Earth Continuity
  2. Lead Polarity
  3.  Insulation resistance
Earth Continuity

This tests the resistance of the protective earth of the electrical appliance.  Tests are done on any accessible earthed part of the appliance and the earth pin of the plug. The earth continuity test is checks the connection between the earth pin and the case of the appliance.

A good connection is usually one that has a resistance of less than 0.1 ohms. An appliance that scores well in the earth continuity test has a vastly reduced likelihood of producing an electrical shock. Class 1 electrical appliances qualify for this test.

Lead Polarity

Most PAT testing machines also come with a lead testing functionality. We first carry out a visual inspection of any leads, cables, cords, or wires. Once the equipment passes the visual inspection, we proceed to carry out PAT testing.

The polarity test determines whether the Live and Neutral are connected correctly to the corresponding terminals in the socket.  If they are reversed, this means the electrical appliance is live, even if it is switched off. If a fault then develops with the appliance, the likelihood of a fire developing is much greater.

Insulation Resistance.

Insulation resistance tests check that there is adequate insulation between the live parts of the appliance and the parts that can be physically touched by the user. The insulation that surrounds the live parts of the appliance must have a high insulation level.

Class 1 and Class 2 electrical appliances are usually subjected to insulation resistance test.

Classes in PAT Testing

Three classes exist:

  1. Class 1
  2. Class 2
  3.  Class 3
Class 1.

This is the most high-risk and potentially dangerous class. Class 1 items usually have only basic insulation and instead rely on the earth for additional protection. Class 1 items will require a complete PAT test.

Examples of Class 1 equipment include

  • Washing machines
  • Vending machine
  • Dishwashers.
  • Microwaves.
  • Kettles.
  • Toasters
  • Desktop computers
  • Phone, laptop, and tablet chargers.
  • Industrial machinery.
Class 2.

These type of appliances have additional insulation and do not rely on the earth. They usually carry less risk as compared to class 1 appliances. Class 2 items will require a minimum of a PAT insulation test but will often not require a complete PAT test.

Examples of Class 2 equipment include

  • Televisions.
  • CD players, DVD players, and radios.
  • Lamps.
  • Hairdryers and hair straighteners.
  • Lawnmowers.
Class 3.

This type of appliance is low voltage. Items categorised as Class 3 are usually low risk and the least dangerous. The appliance itself may not require an in-depth PAT test, although any chargers, wires, or cables will likely need to be tested.

Examples of Class 3 equipment include

  • Cameras
  • Torches
  • Laptops
  • Mobile Phones
Environments Requiring PAT Testing
  1. Hospitality
  2. Educational Establishments
  3. Industrial workplaces.
  4. Commercial environments.
  5. Construction.
  6. Rental properties, both domestic and workplace rentals.
  7. Medical facilities or institutions.
  8. Any environment that is accessible to the public.
PAT Testing Equipment

At Lyghtsource we use a Seaward Primetest 250 PAT tester to carry out inspection works

Seaward Primetest 250 PAT Tester